Firstly, make sure to download and install the Rediff mail app. Secondly, tap the icon of Rediff mail to launch it
Tap on Allow to accept the EULA, then enter your email address and tap on Next.
Now choose your language and tap on Next.
Enter your password and tap Sign in.
Now you will get a prompt for your Rediff mail account.
Read more here:- https://www.datarecovo.com/rediffmail-com-login/